glore2002 said:My question is: What should I do in order to open it to apply grease? and What steps should I follow to adjust the cones? Thanks in advance for your help.
When the time comes, you would use a pair of cone wrenches to open the hub ... remove the cone & nut from the NON-driveside & pull the axle about an inch-or-so from the freehub side IF you are going to regrease the bearings.
The bearings are LOOSE and some will probably fall out when you remove the axle ... so, consider working above a surface that has lips (to catch any bearings that do fall out).
The heavier the grease, the greater the resistance ...
I recommend a white "lithium" grease (fairly "light"😉 ... I think that the grease the Shimano uses depends on the particular hub.
There are two (?) schools of thought with regard to adjusting the cones -- some people pre-load the bearings which I take to mean that they are tighter than I would adjust them ...
I use what I will refer to as the Campagnolo model of ZERO lateral movement of the axle after the cones are adjusted & tightened, but the hub/axle feel SMOOTH when the axle is turned by hand in the hub.
I'm pretty sure that both PARK TOOL & SHELDON BROWN's sites discuss in greater depth ...